Combination of at-sea activity, geolocation and feather stable isotopes documents where and when seabirds molt

• Published in: Frontiers in Ecology and Evolution
• Main Authors: Cherel, Yves, Quillfeldt, Petra, Delord, Karine, Weimerskirch, Henri
• Other Authors: Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: body feathers; flight feathers; inter-breeding period; petrels; Procellariiformes; Southern Ocean; winter; [SDE]Environmental Sciences; Antarc*
• Online Access: https://hal.archives-ouvertes.fr/hal-01291355; https://doi.org/10.3389/fevo.2016.00003

International audience Keyfacetsoftheforagingecologyofseabirdsduringtheinter-breedingperiodstillremainpoorlyunderstoodbecauseofthedifficultyofstudyingthematsea,includingduringtheenergy-demandingmoltingstage.Here,theextenttowhichthreesympatricpetrels(Antarcticandthin-billedprions,andbluepetrel)fromthesubantarcticKerguelenIslandsmodifytheirforagingecologyduringmoltwasinvestigatedusingacombinationofcomplementarytools,namelyminiaturizedsaltwaterimmersiongeolocators(GLS)andtheisotopicmethod.Firstly,moltingbehaviorwasfirstcharacterizedinthebluepetrel,areferencespeciesthatisknowntorenewitsplumageinautumn.GLSandfeatherstableisotopes(13dCasaproxyofthebirds’foraginghabitat)indicatedthatthepost-breedingmoltofbluepetreloccurredinAntarcticwaters.Importantly,activityrecordersshowedthatmoltwasmarkedbyastrongpeakintimespentdailysittingonwater,whichthereafterdeclinedtolowervaluesduringtheremainingwintermonths.Secondly,thepeakintimespentsittingonwaterwasusedasaproxytocharacterizethecontrastedmoltstrategiesofthetwoprionspecies.Asbluepetrelsdemonstrated,thin-billedprionsmoltedduringthepost-breedingperiodincoldAntarcticwaterswheretheyfedprimarilyonlowtrophiclevelprey,mostlikelyAntarctickrill(15dNasaproxyofthebirds’diet).Bycontrast,Antarcticprionspresentedanunexpectedpre-breedingmoltoflongerdurationthattookplacefurthernorth,inwarmsubtropicalwaters.Interestingly,thetwoAntarcticmoltingspecies,thebluepetrelandthin-billedprion,renewedtheirplumageatthesametimeandwithinthesameoceaniczonethatislikelytobeapreviouslyundescribedhotspotofseabirddiversitydurintheAustralautumn.Thestudycontributestoagrowingbodyofevidencethatclosely-relatedspeciesexhibitvariousforagingstrategiesallowingecologicalsegregationandshedsnewlightonthepoorlyknowncriticalmoltingstagefseabirds.